Auckland Prison has been criticised as "a holiday camp" with a maximum-security wing run by the inmates as inept management looks on.
A Corrections officer has launched a scathing attack on prison operations after two inmates were charged with assaulting two fellow workers.
Like all Corrections staff, the officer is not permitted to speak to the media, but he contacted the Herald because he was "fed up and sick of management". He said staff at the prison at Paremoremo had repeatedly warned management that officers in the maximum-security wing were in danger.
"We told them staff are going to get badly assaulted if you don't do anything. We are so short-staffed and management are just chucking anyone in there to make up the numbers ... guys not capable of handling a maximum security unit. They are compromising our safety."
The prisoners in Monday's attack, in the maximum-security wing, allegedly continued to beat one of the officers after they had knocked him unconscious. The second officer was injured when he went to his colleague's aid.
"[Yesterday] the prisoners were laughing about it," the officer said.
"[The victim] was repeatedly kicked in the ribs and the head. He was bashed beyond recognition ... He was motionless. We thought he was dead."
Acting prison manager Jan Taepa said staff safety was at the forefront of department policy. The number of serious assaults by prisoners on staff had fallen from 0.81 per 100 prisoners in 1997-98 to 0.09 in 2005-06.
"Prisons are, however, volatile environments and from time to time staff will be assaulted by prisoners.
"Auckland Prison is home to some of New Zealand's most notorious and manipulative prisoners and staff are constantly on their guard against this type of behaviour."
Ms Taepa said there had been only "very occasional" complaints from staff in the maximum-security unit, which was fully staffed.
Prison officers are allowed to use force only as a last resort, and even then can use only approved control-and-restraint techniques.
But the Herald's informant said the techniques were inadequate. "We need more powers to control those guys. The boys who did that [on Monday] were big boys. The control-and-restraint techniques are no good on them. It's just like tickling them."
He said staff calls for tighter security and better staff protection after a hostage drama at the prison in September - when an inmate held a guard at knifepoint for almost three hours - had fallen on deaf ears.
The most notorious prisoners in the maximum-security wing - including triple murderer William Bell and double murderer Graeme Burton - constantly threatened staff.
"We're basically porters in a hotel. They say jump and we jump because management want to keep the peace. The prisoners run the place.
"There are threats every day from Burton. He threatens to burn the building down, or put out a contract [on prison officers]. Most of the guys are scared of what he did and what he is. He's lost a leg but he's still quite threatening. Every time we take him somewhere there's always seven officers [with] him."
Prisoners in other parts of the jail have privileges that would make the public see red, the informant said.
"They get free medication, watch TV, play pool and table tennis, have barbecues - it's like a holiday camp, not a prison. When they get released, they do something to get back inside."
Ms Taepa rejected the statement that the prison was like a holiday camp, saying recreational facilities provided constructive activity that helped good management of the jail while preparing inmates for reintegration back into the community.